The invention relates to a locking/release mechanism for a pivot bolt of a closed-circuit door opener with a safety catch for the pivot bolt, which is controlled by an electromagnet.
Unlike in the case with normal door openers having an operating current function, with closed-circuit door openers the pivot bolt is movable when the electromagnet is currentless or dead and the door can be opened. If the closed-circuit door opener magnet is live, the safety catch is stopped by the action of the electromagnet, so that a closed door cannot be opened. However, if the circuit is cut or interrupted in the case of a power failure, the pivot bolt is freed, so that the door can be opened and closed in random manner.
Such closed-circuit door openers operate in a very reliable manner. However, in exceptional circumstances, where a person exerts a strong pressure on the pivot bolt prior to the cutting out or interruption of the magnet current, there is a risk of the lever mechanism jamming, which prevents the release of the pivot bolt.